Question

Create Outer boundary

S
Hi Folks,

 

 

I have a requirement of browsing parcel boundaries with particular attribute value and create a outer boundary for all browsed parcel boundaries. Here the browsed parcel boundaries are not all connected together, there are some gaps between the parcel boundaries.

 

Please guide me that how can I outer line for parcel boundaries.

 

Thanks in Advance.

 

 

Regards,

 

Seshu

9 replies

david_r
Rank
Userlevel 4
Hi,

 

 

if you only need a rough outline, you could use a HullAccumulator (concave) with a Group By. You will have to play with the Alpha-value depending on the size of your gaps.

 

 

For a more precise solution, you will have to do this in several steps. For example use a Bufferer with X units on all objects so that all gaps are removed, then dissolve with Group By and then finally a Bufferer with -X units to shrink the objects back to their original size.

 

 

David
G
Badge +3
Buff dissolve and buff again, requires search for maximum required buff.

 

 

Another way to do this, bit more elaborate, but automated.

 

  1. Create a hull.
  2. SpatialRelate parcels with this Hull. Use calculate cardinality. Acquire the parcel-intersections with line_cardinality. (u nee to manually expose this attribute)
  3. geomterycoerce outer boundary of Hull to line.
  4. chopp this up max. vert =1
  5. Toppology create: Hull as line and the chopped verts as nodes.
  6. chopp parcellines from step. 2. Max. vert =1
  7. use neigbhourfinder to find closest node on line to endpoints from 6. This to couple the nodecoutnattribute (nodenumber) to endpoints of the parcellines from step. 2
  8. at this stage endpoints have nodenrs. These are ordered. U can now put a counter on it to set countstart to 0 or 1. (not required, but looks better)
  9. Use a sorter on the counter.
  10. now endpoints are ordered so u can use pointconnector.
This should give u a closed polyline running along the boundary of the parcels.
G
Badge +3
"endpoints form 6" should read "points from 6"
G
Badge +3
Without any rules it is a bit arbitrary..so this leads to many ways to do this.
takashi
Rank
Userlevel 2
Badge +17
Hi,

 

 

Just today I created a workspace to perform a job similar to yours.

 

In my case, gaps were very small, so I used the Snapper (Snapping Type: Segment Snapping)  and the Dissolver to get outer boundaries of polygons.

 

But the Snapper could create many self-intersections on polygon boundaries, and the Dissolver droped some input polygons when they have self-intersections.

 

So, I've also used the GeometryValidator to repair self-intersections before dissolving.

 

Finally the workspace worked fine :)

 

FYI.

 

 

Takashi
f.kemminje
Badge +3

@takashi , I have same requirement can you pls help

B
Buff dissolve and buff again, requires search for maximum required buff.

 

 

Another way to do this, bit more elaborate, but automated.

 

  1. Create a hull.
  2. SpatialRelate parcels with this Hull. Use calculate cardinality. Acquire the parcel-intersections with line_cardinality. (u nee to manually expose this attribute)
  3. geomterycoerce outer boundary of Hull to line.
  4. chopp this up max. vert =1
  5. Toppology create: Hull as line and the chopped verts as nodes.
  6. chopp parcellines from step. 2. Max. vert =1
  7. use neigbhourfinder to find closest node on line to endpoints from 6. This to couple the nodecoutnattribute (nodenumber) to endpoints of the parcellines from step. 2
  8. at this stage endpoints have nodenrs. These are ordered. U can now put a counter on it to set countstart to 0 or 1. (not required, but looks better)
  9. Use a sorter on the counter.
  10. now endpoints are ordered so u can use pointconnector.
This should give u a closed polyline running along the boundary of the parcels.

 

Hi gio,

 

Can you please show me an example of the above solution, because I do not fully understand what you meaning...

 

For example do an FME workspace with my applied three Shape files input.zip

 

Thanks in advance!

 

Best regards,

 

Jonas
mark2atsafe
Rank
Userlevel 4
Badge +25

 

Hi gio,

 

Can you please show me an example of the above solution, because I do not fully understand what you meaning...

 

For example do an FME workspace with my applied three Shape files input.zip

 

Thanks in advance!

 

Best regards,

 

Jonas
Hi @bigjonas69 - it would probably be better to post a new question. I think more people will see it and be able to help. But I'll also take a look and see if I can apply the above solution.

 

B
Hi @bigjonas69 - it would probably be better to post a new question. I think more people will see it and be able to help. But I'll also take a look and see if I can apply the above solution.

 

Hi Mark,

 

Yes please take a look at it and see if you can create a simple example of it...

 

Thanks in advance!

 

Best regards

 

Jonas

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